Download General specification for three-phase

General specification for three-phase
oil-immersed in the mineral oil HV/LV distribution transformers
100 to 2500 kVA
1 - Scope
Three-phase oil-immersed transformers, hermetically sealed with integral filling,
insulation system with oil natural air natural (ONAN) cooling for indoor or outdoor
installation, destined for use in three-phase HV/LV distribution systems .
The transformers have reduced losses , type BoAk ( table of EN 50464 standarts)
following the specification of synergrid ( march 2011 )
2 - Standards
These transformers will be in compliance with the following standards :
- NBN C52 101 à 105
- IEC 60076.01 to 60076.05
- NBN EN 50464
- IEC 354 edition dated 1991- Loading Guide for oil-immersed type power transformers.
These transformers will be manufactured in accordance with :
- a quality system in conformity with ISO 9001
- an environmental management system in conformity with ISO 14001, both certified
by an official independent organisation.
3 - Description
3.1 - magnetic core
This will be made from laminations of grain oriented silicon steel, insulated with mineral
oxide; the method of cutting and stacking will be "step lap", so as to optimise the level
of no-load losses.
3.2 - LV windings
These will be made from copper profile wire or aluminium or copper foil (according to
the manufacturer's preference ) .
3.3 - HV windings
These will be made of copper profile wire or aluminium or copper round wire (according
to the manufacturer's preference) .
3.4 - HV connections
The standard HV connections will use porcelain bushings on the top of the transformer.
Fixed HV plug-in bushings 24 kV 250A, with HV mobile plug-in bushings - straight or
elbow according to the orientation of the incoming cables - may be provided as an
option.
3.5 - LV connections
The LV connections will be made using porcelain bushings up to 500 kVA, and flat-bars
from 630 kVA onwards.
LV porcelain bushings from 630 kVA are also available on request.
A LV air-insulated terminal cover may be provided as an option.
3.6 - HV tapping
The tapping which act on the highest voltage adapting the transformer to the real
supply voltage value, will be provided with an off-circuit tap-changer switch with a
padlocking facility on the top cover of the transformer.
4 - Accessories and standard equipment
These transformers will be equipped with :
- 4 bi-directional flat rollers
- 2 lifting and untanking lugs
- 2 earthling terminals
- 1 filling plug
- 1 draining device
- 1 rating plate
- 1 routine test certificate
5 - Protection




These transformers will be equipped in option with a protection relay , DMCR or similar
, these including :
1 gas detector/flow level indicator with one contact (for gas discharge and drop in
liquid level)
1 over-pressure contact (for internal pressure increase)
1 thermostat with 2 contacts for alarm and tripping (for internal temperature increase)
1 dial type thermometer without contact.
6 - Main characteristics of construction
6.1 - tank
The tank of the transformer will be made with flexible cooling corrugations, in order to
absorb the expansion of the dielectric due to temperature variations.
The cover will be bolted on top of the tank.
The tank will be built in such a way as to avoid any water accumulation.
6.2 - dielectric and component material
The dielectric will be minerale oil following Iec 297 standards.
The concentration in PCB (polychlorobiphenyl) has to be lower than the minimum
detection rate of 2 ppm (parts per million).
The components of the transformer such as insulation material, varnish, painting, etc.
have to be new and PCB-free.
The filling of the transformer will be made under vacuum, in order to guarantee the
maximum preservation of dielectric properties.
The live part of the transformer will be previously oven dried so as to remove all
residual humidity.
6.3 - gaskets
All the gaskets (in general made of elastomer) have to be resistant against the action of
the minerale oil, at the working temperature.
6.4 - protection against corrosion
The main characteristics of the coating guarantee following norm ISO 19444-2
Category C3 , medium durability RI 3 – 5 year
Colour : RAL 7033
7 - Electrical tests
7.1 - routine tests
These tests will be carried out on all the transformers after the manufacturing, enabling
an official test certificate to be produced for each one :
- applied voltage dielectric test
- induced voltage dielectric test
- measurement of no load loss and no load current
- measurement of windings resistance
- measurement of impedance voltage and load loss
- measurement of the transformation ratio and vector group
(All these tests are defined in the IEC 60076-1 to 60076-5 standards).
7.2 - type tests or special tests
These tests can be requested as option, but are subject to prior agreement of the
supplier :
- temperature rise test
- lightning impulse test
- measurement of partial discharges.
- short circuit test (implemented in an approved laboratory)
- noise level measurements in accordance with IEC 60076-10.
(All these tests are defined in the IEC 60076-1 to 60076-5 standards).
Technical Data
For each requested transformer, the supplier will give the following data :
Rated power ................................................................................................................
Cooling.........................................................................................................................
Quantity .......................................................................................................................
Rated frequency ...................................................................................................... 50
Rated primary voltage .................................................................................................
Rated primary insulation level .............................................................................. 17.5
Applied voltage to industrial frequency (50 Hz/1 min) ............................................. 38
Basic Insulation Level (BIL) or impulse (1.2/50 µ) ................................................... 95
Off-circuit tapping .................................................................................. +- 2.5 +- 5 %
Secondary voltage at no load
between phases ....................................... 420
phase to neutral ....................................... 242
Rated secondary insulation level
.................................................................. 1.1
Applied secondary voltage to industrial frequency ................................................. 2.5
Vector group .................................................................................................... Dyn 11
kVA
ONAN
No load losses .............................................................................................................
Load losses at 75° C ...................................................................................................
Rated impedance voltage at 75° C ..............................................................................
Acoustic power Lw(A) ..................................................................................................
Acoustic pressure at 0.3 metre Lp(A) ..........................................................................
W
W
%
dB(A)
dB(A)
Maximum ambient temperature ............................................................................... 40
Daily average ambient temperature ........................................................................ 30
Yearly average ambient temperature ...................................................................... 20
Maximum altitude ................................................................................................ 1000
°C
°C
°C
m
Temperature rise of windings .................................................................................. 65
Temperature rise of dielectric .................................................................................. 60
K
K
Length ..........................................................................................................................
Width............................................................................................................................
Height ..........................................................................................................................
Total weight .................................................................................................................
Dielectric weight ..........................................................................................................
mm
mm
mm
kg
kg
Hz
kV
kV
kV
kV
V
V
kV
kV